Air-cooled rotary internal combustion engine

ABSTRACT

An air-cooled rotary vane engine utilizing external and internal cooling air flow and a turbulence combustion chamber controlled by an automatic valve operated by the working fluid pressures; the engine is further constructed for operation with clearance sealing and dry internal lubrication.

United States Patent Bendall Jan. 1, 1974 AIR-COOLED ROTARY INTERNAL1,987,882 1 1935 Watts 418/101 x COMBUSTION ENGINE 2,969,049 1/1961Dillenberg 3,369,529 2/1968 Jordan 418/101 X [76] Inventor: Wilfrid H.Bendall, 19 N. Broad St.,

Pawcatuck, Conn. 02891 Filed: Nov. 1972 Primary ExammerClarence R.Gordon [21] Appl. No.: 305,334

[57] ABSTRACT [52] US. Cl 60/39.6l, 123/809, 123/827,

418/101 An air-cooled rotary vane engine utilizing external and [51]Int. Cl. FOZC 5/12 i li g air flow and a turbulence combustion [58]Fleld of Search 60/3961; chamber ontrolled by an automatic valveoperated by 8-09, 8-19, the working fluid pressures; the engine isfurther constructed for operation with clearance sealing and dry 156]References cued internal lubrication.

UNITED STATES PATENTS 891.394 6/1908 Benson 60/39.:31 UX 21 Claims, 6Drawing Figures PAIENIEUm 11974 3.782.107

SHEET an; 3

SEEN 3 0F 3 FIG.S-

AIR-COOLED ROTARY INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTIONRotary engines in general and particularly those at present underintensive development utilizing multilobed epitrochoidal housings andvariously contoured eccentrically orbiting rotors, present formidablecombustion, sealing and cooling problems which tend to negate thecompelling simplicity of the rotary principle and its potentiallysimpler construction, lower cost and lighter specific weight.

The desirable air-cooling of such engines further presents specialdifficulties and the principal purpose of the present invention is toprovide such an engine of simpler construction and minimum bulk andweight particularly adapted for efficient air-cooled operation.

SUMMARY OF THE INVENTION Accordingly, the engine of the presentinvention employs a uniformly cylindrical housing and rotor withcircumferential external and internal cooling fins and withprovision forexternally and internally directed cooling air flow. Operation withuniform angular rotation at the more convenient shaft speeds and withthe larger sealing areas permitted by the rotary vane arrangementconveys the further advantage of more manageable pressure sealingconditions than is possible with trochoidal engine configurations. Thepresent engine therefore is designed to enable operation with minimallyclose running clearances to effect restricted clearance sealing of theoperating interstices without requiring solid frictional sealing contactor lubrication at the critical pressure and thermal regions of theengine structure. In furtherance of these objects and in order to effectefficient combustion at high cyclical rates the design includes a highturbulence cylindrical combustion chamber interposed between sequentialcompression, combustion and expansion phases. This arrangement increasescombustion efficiency and insulates the main engine structure frommaximum thermal and dynamic stresses. Adaptability for multi-fueloperation is conveyed by the provision of means whereby the compressionratio and ignition means can be varied without major structural changes.Pumpless fuel injection may be effected by placement of simple lowpressure feed injection nozzles in the combustion chamber communicatingpassage means. The uniformly round housing and combustion chamber endclosures secured by cylindrical groove engagement retention means inplace of a multiplicity of fastenings, lowers construction and assemblycosts, conveys maximum accessibility and maintenance convenience, andprovides a simple, reliable engine structure with a high power to weightratio.

DESCRIPTION OF THE DRAWINGS FIG. 1 is transverse partly diagrammaticsectional view of an air-cooled rotary internal combustion engineembodying the invention taken substantially along line 1-1 of FIG. 2;

FIG. 2 is a sectional view taken substantially along line 2-2 of FIG. 1;

FIG. 3 is an end elevational view of a rotary vane member of the engineof this invention;

FIG. 4 is a sectional view of the vane taken along line 4-4 of FIG. 3;

FIG. 5, on a larger scale, is a fragmentary sectional view of acombustion chamber and automatic valve of the engine of this invention;

FIG. .6 is a sectional view on the line 6-6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings,specifically to FIGS. 1 and 2, reference numeral 10 generally designatesa rotary engine according to this invention. The engine comprises acylindrical outer body 12 provided with external cooling fins 14 andhaving an internal peripheral wall 16 enclosed by axially spaced endwalls 18. A cylindrical inner body comprising rotor 20 is provided withinternal cooling fins 22 and integral end walls 24. The rotor, keyed toa one-piece axis 26 extending through both bodies, is mountedeccentrically within the outer body and rotatably supported in sealedlubrication bearings 28. As shown, the bearing races center the rotor onaxis 26 with respect to the outer body and are retained in the outerbody end walls by retaining ring means 29.

The rotor outer peripheral and end surfaces are in minimally closerotational clearance with the inner peripheral and end walls of theouter body, the eccentric mounting of the rotor defining acircumferentially extending crescent-shaped displacement chamber 30having working fluid inlet passage 32 and outlet passage 34. The rotor20 further comprises two symmetrical coaxial halves abutting on acenterline joint 36 having locating dowels 38. Cylindrical sealing ringsegments 40 engage coaxial grooves in the two halves of the joint. Theouter peripheral surface and annular portions 41 of the rotor in closerotational clearance with the outer body may be provided with turbulencesealing grooves (not detailed) or a layer of abradable sealant tofurther reduce the rotor running clearance.

Slots 42 in the rotor are provided with self-aligning, self-lubricatedbearing elements 44 extending axially and supporting the combinedangular and radial motion of vane members 46. The vane members,individually illustrated in FIGS. 3 and 4, are provided with offsetinner end ring portions 48 for intermeshing with similar coaxial ringportions of an oppositely extending vane and are eccentrically centeredfor rotation relative to the rotor and axis 26 on stationary vanecentering means 50 encircling the axis. As shown, centering means 50 maycomprise a cylinder in offset suspension on axis 26, stationary withrespect to the axis rotation and concentric with the outer body. Thecentering means preferably is constructed of lubricantimpregnatedsintered metal or other self lubricated material, the operating load andPV bearing factors on this member normally being moderate enough toenable use of such material. The member may be recessed as indicated byreference numeral 58 for weight reduction or cooling purposes and mayinclude axial grooves 60 at the inner peripheral contact with the vanerings for passage of cooling air.

The vanes are thus centered for rotation with their side and outer endportions in minimally close running clearance in the displacementchamber. The vane outer end portions 52 are bored out to provideinternal cooling air passages 54 and 55 and to reduce centrifugalweight, the ring shaped inner ends 48 being provided withcounterbalancing weights 56 secured in slots in the ring ends. The outerends of the vane cooling air passages 54 are shown closed with plugs 57,preferably of porous material. Alternatively a larger plurality of suchvane cooling air passages, of smaller relative sectional area, may beused and left open at their outer ends.

Shown on a larger scale in FIGS. 5 and 6, the cylindrical combustionchamber 72 integral with the outer body and external to displacementchamber 30, is provided with communicating inlet and outlet passages 70and 80, respectively. The combustion chamber ends are closed withremovable cylindrical closure plugs 72a, and retained by groove insertedrings 72b. This arrangement facilitates changes of compression ratio andignition means, such as indicated by dash outline 72f, by changing plugaxial lengths and ignition component inserts. The cylindrical plugs areprevented from rotating and are oriented with respect to each other andpassages 70 and 80 by pins 720 engaging slots 72d in the combustionchamber bore. The plugs further serve to locate and retain an automaticvalve 76, a light semicircular member with integral stiffening flanges,constructed of heat resistant material and supported for freeoscillation on pivotal pin 72e extending between the plugs. This memberis not required to be pressure tight and functions essentially as abaffle separating the cyclical operating phases in response to fluidpressure changes through the communicating passages, the portion 78 ofthis member on the combustion chamber outlet side being provided with ashorter effective pressure arm with respect to its pivotal center thanthe pressure arm of its opposite portion 74 on the inlet side.

An important feature of this invention is its provision for a continuousinflux of cooling air throughout the engine structure during operation.The inherent pumping action of the vanes in the rotor body entrainscooling air through apertures 86 in the outer body end walls 18 andthence through clearance apertures 88 in the inner body end walls 24,the air flowing to the rotor interior as indicated by arrows 87. Airthus continuously pumped into the rotor interior is centrifuged to therotor fins 22 and subsequently expelled through the vane and rotoroperating clearances. Internal cooling air is further drawn out throughvane slots 90 to the exhaust outlet 34. These cooling flows aresupplemented by a continuous centrifugally induced counterflow throughthe vane and rotor operating clearances which usefully opposes thecyclical compression and expansion pressures. External cooling of theengine is effected by air inducted between the shrouded cooling fins 14encircling the outer body. Air is drawn to aperture 92 by the normalinterfin heat flow supplemented by the exhaust efflux at passage 34. Thefin shrouding means 96 embodies a plurality of circumferentially spacedapertures 97 registering with the interfm passages for furtherentrainment of ambient air external to the engine.

The cooling method thus described permits engine operation at highermaximum and mean cycle temperatures and proportionately lower exhausttemperatures, and thus with higher combustion efficiency than attainablewhere free lubrication and contact sealing requirements limit andpollute engine performance. It will be noted that substantially theentire working and cooling fluid volume flows unidirectionally throughthe compression, combustion and expansion compartments. In operation,with the rotor turning as indicated by arrow 62 in FIG. 1, the righthand vane is compressing the working fluid in advance of its leadingface 64 and is inducting a fresh charge through inlet 32 with thesuction generated by its following face 66. High velocity flow inadvance of the vane compression face reduces pressure at the fuel supplynozzle 68 for admission of fuel into passage 70 and thence to combustionchamber 72. Pressure in passage 70 has opened the inlet portion 74 ofautomatic valve 76 and simultaneously closed its combustion chamberoutlet portion 78 leading to passage 80. The subsequent combustion andexpansion simultaneously activates the valve to close passage 70 andopen passage 80 for expansion of the working fluid against theretreating face 82 of the left hand vane. The leading face 84 of theleft hand vane is simultaneously sweeping out a mixture of combustiongases and cooling air inducted during the preceding phase. An exhaustcheck valve (not shown) may be located at the exhaust outlet 34 but isnot considered essential, the exhaust inertia being sufficient to effectsubstantial clearing during the expansion phase with a permissibleadmixture of inlet air.

While the drawing show the engine without the usual accessories, thedash outline 98 at the left side of FIG. 2 indicates an integral flangedextension of the outer body end wall which may be utilized forattachment of duplicate engine units and such starting, fuel pump andignition devices as may be preferred, and also for attachment of engineinstallation bearers.

In comparison, the output torque of the twin-vane single rotor engine ofthis invention equals that of the double rotor epitrochoidal configuredengines, without involving a negative torque component and in astructure with substantially half the weight, bulk and production cost.lts valve controlled combustion chamber and lubricant limited operationprovides cleaner, more economical and more versatile combustionconditions, conveniently modifiable for various operating cycles. Thestructural design further reduces the required number of parts to aminimum and conveys maximum accessibility for economical maintenance.

What is claimed is:

1. An air-cooled rotary internal combustion engine comprisingcircumferentially finned outer and inner bodies, both of said bodieshaving axially spaced end walls provided with a plurality of aperturesfor admission of cooling air, said inner body being eccentricallymounted for rotation within the outer body on an axis concentrictherewith and extending through both bodies, axis bearing means in saidouter body end walls maintaining the inner body in minimally closeinternally tangential running clearance, said bodies being juxtaposed todefine a circumferentially extending, crescent-shaped displacementchamber between the facing surfaces, said outer body having workingfluid inlet and outlet passage means communicating with the chamber,said inner body having axially extending peripheral slots and radiallydisposed vanes, with vane outer end portions extending through theslots, said vanes having annular inner end portions axially mounted forrotation on centering means concentric with the outer body and eccentricof the inner body, said centering means being stationary with respect toaxis rotation and maintaining the vanes for rotation thereon with theirouter end portions in minimally close running clearance with the innersurface of the outer body, said vane outer end portions definingvariable volume working chambers comprising abutment means for theworking fluid cyclical intake, compression, expansion and exhaust phasesin said chamber and said vane inner end portions comprising inner bodyabutment and displacement means for a working fluid inducted throughsaid end wall apertures, a combustion chamber external to thedisplacement chamber interposed between said compression and expansionphases and having working fluid admission and transfer passage meanscommunicating therewith at circumferentially spaced sides of the regionof inner body tangency, said combustion chamber including valve meansoperated by transfer passage compression and expansion pressures.

2. A rotary engine as defined in claim 1 wherein the end walls of theinner body are provided with a plurality of apertures for passage ofcooling air inducted through outer body apertures.

3. A rotary engine as defined in claim 1 wherein the inner body furthercomprises two coaxial and abutting cylindrical halves with registeringmeans at a circumferential abutting line.

4. A rotary engine as defined in claim 3 wherein the inner body halvesare provided with circumferential, axially spaced internal cooling fins.

5. A rotary engine as defined in claim 1 wherein the outer body andwalls comprise cylindrical discs having axial hub portions and bearingportions for sliding assembly in the bore of the outer body andretention therein by annular retaining rings.

6. A rotary engine as defined in claim I wherein the outer body isprovided with axially spaced circumferential cooling fins and finshrouding means having a plurality of apertures registering withinterfin spaces to entrain cooling air inducted through said aperturesby the interfin air flow.

7. A rotary engine as defined in claim 1 wherein the vane members haverectangular-sectioned outer end portions engaging rotor slots andannular inner end portions engaging stationary axially mounted centeringmeans.

8. A rotary engine as defined in claim 7 wherein the centering meansincludes an internal bearing on the axis and external bearing means forvane members.

9. A rotary engine as defined in claim 1 wherein the vane outer endportions embody a plurality of internal cooling air passages.

10. A rotary engine as defined in claim 1 wherein the combustion chamberis cylindrical in form and axially parallel to the displacement chamber.

Ill. A rotary engine as defined in claim 10 wherein the combustionchamber ends are closed by axially spaced removable cylindrical plugssecured by annular retaining means.

12. A rotary as in claim ll wherein the engine compression ratio isadjustable by changing the axial length and spacing of the cylindricalplugs.

13. A rotary engine as defined in claim 1 wherein the valve meanscomprise a centrally pivoted semi-circular member having portions eachside of the pivotal center shaped to conform to the combustion chamberwall at said communicating passages.

14. A rotary engine as defined in claim 13 wherein the valvesimultaneously opens and closes the transfer passage means.

15. A rotary engine as defined in clain 1 wherein working pressures aresubstantially contained by minimally close adjacent surfaces withoutloaded rubbing or frictional contact and without fluid lubrication.

16. A rotary engine as defined in claim 15 wherein the bearing membersare integrally sealed and lubricated, whereby exhaust pollutinglubricating oil consumption by the engine is eliminated.

17. A rotary engine as defined in claim 1 wherein rotation of the vaneswithin the inner body inducts cooling air through apertures in the outerand inner body end walls and expels it through vane and inner bodyoperating clearances for subsequent discharge through a displacementchamber outlet.}

18. A rotary engine as defined in claim 17 wherein substantially theentire internally inducted working and cooling fluid volume is passedthrough displacement and combustion chambers and is expelled through adisplacement chamber outlet passage.

19. A rotary engine as defined in claim 7 wherein the annular inner endportions of the vane members are weighted to balance the weight of theouter end portions.

20. A rotary engine as defined in claim 1 wherein the inner body isaxially centered between the outer body end walls by inner body abutmentwith an inner bearing member and outer bearing member abutment with theouter body.

21. A rotary engine as defined in claim 1 wherein said transfer passageincludes fuel supply means arranged for activation by working fluidpressure changes in said passage.

1. An air-cooled rotary internal combustion engine comprisingcircumferentially finned outer and inner bodies, both of said bodieshaving axially spaced end walls provided with a plurality of aperturesfor admission of cooling air, said inner body being eccentricallymounted for rotation within the outer body on an axis concentrictherewith and extending through both bodies, axis bearing means in saidouter body end walls maintaining the inner body in minimally closeinternally tangential running clearance, said bodies being juxtaposed todefine a circumferentially extending, crescent-shaped displacementchamber between the facing surfaces, said outer body having workingfluid inlet and outlet passage means communicating with the chamber,said inner body having axially extending peripheral slots and radiallydisposed vanes, with vane outer end portions extending through theslots, said vanes having annular inner end portions axially mounted forrotation on centering means concentric with the outer body and eccentricof the inner body, said centering means being stationary with respect toaxis rotation and maintaining the vanes for rotation thereon with theirouter end portions in minimally close running clearance with the innersurface of the outer body, said vane outer end portions definingvariable volume working chambers comprising abutment means for theworking fluid cyclical intake, compression, expansion and exhaust phasesin said chamber and said vane inner end portions comprising inner bodyabutment and displacement means for a working fluid inducted throughsaid end wall apertures, a combustion chamber external to thedisplacement chamber interposed between said compression and expansionphases and having working fluid admission and transfer passage meanscommunicating therewith at circumferentially spaced sides of the regionof inner body tangency, said combustion chamber including valve meansoperated by transfer passage compression and expansion pressures.
 2. Arotary engine as defined in claim 1 wherein the end walls of the innerbody are provided with a plurality of apertures for passage of coolingair inducted through outer body apertures.
 3. A rotary engine as definedin claim 1 wherein the inner body further comprises two coaxial andabutting cylindrical halves with registering means at a circumferentialabutting line.
 4. A rotary engine as defined in claim 3 wherein theinner body halves are provided with circumferential, axially spacedinternal cooling fins.
 5. A rotary engine as defined in claim 1 whereinthe outer body end walls comprise cylindrical discs having axial hubportions and bearing portions for sliding assembly in the bore of theouter body and retention therein by annular retaining rings.
 6. A rotaryengine as defined in claim 1 wherein the outer body is provided withaxially spaced circumferential cooling fins and fin shrouding meanshaving a plurality of apertures registering with interfin spaces toentrain cooling air inducted through said apertures by the interfin airflow.
 7. A rotary engiNe as defined in claim 1 wherein the vane membershave rectangular-sectioned outer end portions engaging rotor slots andannular inner end portions engaging stationary axially mounted centeringmeans.
 8. A rotary engine as defined in claim 7 wherein the centeringmeans includes an internal bearing on the axis and external bearingmeans for vane members.
 9. A rotary engine as defined in claim 1 whereinthe vane outer end portions embody a plurality of internal cooling airpassages.
 10. A rotary engine as defined in claim 1 wherein thecombustion chamber is cylindrical in form and axially parallel to thedisplacement chamber.
 11. A rotary engine as defined in claim 10 whereinthe combustion chamber ends are closed by axially spaced removablecylindrical plugs secured by annular retaining means.
 12. A rotary as inclaim 11 wherein the engine compression ratio is adjustable by changingthe axial length and spacing of the cylindrical plugs.
 13. A rotaryengine as defined in claim 1 wherein the valve means comprise acentrally pivoted semi-circular member having portions each side of thepivotal center shaped to conform to the combustion chamber wall at saidcommunicating passages.
 14. A rotary engine as defined in claim 13wherein the valve simultaneously opens and closes the transfer passagemeans.
 15. A rotary engine as defined in claim 1 wherein workingpressures are substantially contained by minimally close adjacentsurfaces without loaded rubbing or frictional contact and without fluidlubrication.
 16. A rotary engine as defined in claim 15 wherein thebearing members are integrally sealed and lubricated, whereby exhaustpolluting lubricating oil consumption by the engine is eliminated.
 17. Arotary engine as defined in claim 1 wherein rotation of the vanes withinthe inner body inducts cooling air through apertures in the outer andinner body end walls and expels it through vane and inner body operatingclearances for subsequent discharge through a displacement chamberoutlet.
 18. A rotary engine as defined in claim 17 wherein substantiallythe entire internally inducted working and cooling fluid volume ispassed through displacement and combustion chambers and is expelledthrough a displacement chamber outlet passage.
 19. A rotary engine asdefined in claim 7 wherein the annular inner end portions of the vanemembers are weighted to balance the weight of the outer end portions.20. A rotary engine as defined in claim 1 wherein the inner body isaxially centered between the outer body end walls by inner body abutmentwith an inner bearing member and outer bearing member abutment with theouter body.
 21. A rotary engine as defined in claim 1 wherein saidtransfer passage includes fuel supply means arranged for activation byworking fluid pressure changes in said passage.